langgraph-python-quickstart

Builds LangGraph's quickstart calculator agent in Python, a small agent that does arithmetic with tools, laid out as a graph of steps and run on the model of your choice.

WHEN TO USE

SCOPE

USE FOR

Build the math agent with LangGraph's Graph API, as the live docs show it.
Replace the docs' hardcoded Anthropic model with whichever model you choose.
Set up the example in a new folder so your current project is left alone.
Ask it to add 3 and 4 and check the answer comes back.
See where to go next, or switch to LangChain's simpler agent API instead.

This is a saved copy of the skill's SKILL.md instructions. It may differ from the upstream file or the version you install.

In this document (2)

LangGraph Python quickstart

Follow the live docs — do not invent an alternate API from memory:

https://docs.langchain.com/oss/python/langgraph/quickstart

Fetch that page (Docs MCP or HTTP) and implement what it shows (calculator / math agent with the Graph API). Prefer the Graph API path over the Functional API unless the user asks otherwise. Skip IPython graph visualization.

Local setup constraints

Apply these on top of the quickstart (they keep setup minimal and model-agnostic):

Ask which provider/model to use. Showcase that LangGraph works with any LangChain chat model. Suggested prompt:

Which model should this agent use? Pass a provider:model string — e.g. openai:gpt-5.5, anthropic:claude-sonnet-5, google_genai:gemini-2.5-flash-lite. Default if you're unsure: anthropic:claude-sonnet-5.

The docs often hardcode Anthropic — replace with init_chat_model("<MODEL>") (or equivalent) using their choice. If using Claude Sonnet 5+, omit temperature / top_p / top_k (unsupported).
Create a new directory (e.g. langgraph-agent/) and do all work there — do not pollute the open project.
Only secret: the provider API key in .env (gitignored). No LangSmith / Tavily unless they ask. Prefer they edit .env themselves — don't paste keys into chat.
Install packages from the quickstart plus the provider package for their model.
Run the example (e.g. “Add 3 and 4.”), show output, then stop. Point to langgraph-fundamentals for next steps. For a higher-level agent API, use LangChain create_agent instead.

This skill ships inside the LangChain Agent-Building Skills plugin.

Install just this skill

Run this outside your AI tool, using Node.js 22.20.0 or newer. Skills CLI 1.7.2 skips skill selection; prompts cancel installation without an interactive terminal. If choosing Project when asked about installation scope, open your project's folder before running this.

Install checklist

Check selected tools if a picker appears; Claude Code may be unchecked under Additional agents. ↑/↓ moves, Space toggles selections, Enter confirms.
Without a tool picker, check Installing to: for your intended tool. Stop if it names a different tool.
If asked, choose Symlink (Recommended) for shared files or Copy to all agents for separate copies; review the summary before confirming installation.
Install the find-skills skill? defaults to Yes, adding another skill for all projects. Choose No if you don't want that extra installation.

Skills CLI 1.7.2 sends install data to skills.sh by default, including the source, skill names, target tools and file details; GitHub sources are reported only when GitHub confirms the repository is public, while other remote sources can also be reported. Confirmed-public GitHub sources also trigger a security-audit request. Before installing, set the environment variable DO_NOT_TRACK=1 or DISABLE_TELEMETRY=1 to disable both.

npx skills add langchain-ai/langchain-skills --skill "langgraph-python-quickstart" --full-depth

After installing for Claude Code, open it in the installation project if you chose Project; Global makes the skill available across projects on this computer. Once Claude Code loads the skill, its description helps Claude decide when to use it.

If installation created a top-level skills folder that did not exist when your Claude Code session started, run /reload-skills in that session. Run it again after later changes in that folder.

Install the whole plugin

This route installs the LangChain Agent-Building Skills plugin package selected for your AI tool.

Claude Code

Add LangChain's marketplace, then install the plugin

Type both lines inside a Claude Code session, not at your shell prompt. The first adds LangChain's marketplace, which is this repository; the second opens the details of the langchain-skills plugin, and Claude Code installs it once you pick one of the install options shown. Afterwards, LangChain's README asks you to set OPENAI_API_KEY or ANTHROPIC_API_KEY, for whichever of those model providers you build with.

/plugin marketplace add langchain-ai/langchain-skills

/plugin install langchain-skills@langchain-skills

Open plugin page ↗

View on GitHub

LangGraph Python quickstart

Local setup constraints

Account or credentials required

Install just this skill

Install the whole plugin

Add LangChain's marketplace, then install the plugin

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